1. Field of the Invention
The present invention relates to a process for the continuous production of a surface-consolidated lumber and also to a surface-consolidated lumber produced according to this process.
2. Description of the Prior Art
Attempts have heretofore been made to improve the abrasion resistance or damage resistance of a lumber by consolidating its surface layer to increase the surface hardness. For example, there can be mentioned a method in which a lumber is impregnated with a resin [see, for example, "Mokuzai-Kogyo Handbook" (Handbook of Wood Industry), 3rd revised edition, pages 467 through 474 (1982)] and a method in which a lumber is hot-pressed on a flat-platen press.
According to the conventional resin impregnation method, however, the whole of a lumber to be treated is highly densified so that it is very difficult to consolidate only its surface layer and the whole of the lumber, that is, not only the surface layer but also the internal layers are highly densified. Accordingly, the amount of a treating agent to be used is inevitably increased, resulting in an increase in the cost, and the specific gravity of the treated lumber becomes too high.
According to the method using a flat-platen press, it is possible to consolidate only the surface layer of a lumber to be treated, but the size of a lumber to be treated is restricted by the size of the press and therefore the production cannot but be conducted batchwise and the production efficiency is inevitably low.